How to made model of a small river push boat with Orca3D Hull Assistant and Delftship

Heimfried, true, now I see it. I could not understand what you said but you are right. I apologize for being so closed-minded.
If there is any incorrect statement of mine, I pray you tell me, I'll swallow my pride and recognize. As someone has said somewhere, I learn more from my mistakes than from my successes.
My apologies again.
Taking advantage of the occasion and since you seem to have more knowledge, which means "Max.GZ at 0º greater = 1.084". I think that if the boat has not an initial list, the GZ at 0º should be = 0.

 

Naturally the GZ at 0° ist 0 m.

In the diagram is written: "Max GZ at 0° or greater = 1.084 ...". I think, it is capable of being misunderstood. I don't know, if it is automatically written by the software or commented by the poster.

In my opinion the meaning is simply: "There is a Maximum of GZ in the diagramed interval of the curve, starting with 0° and increasing. Its value is 1.084 m . "

 

Again I was wrong and I have transcribed the text incorrectly. Indeed, the GZ curve values seems to have a maximum value a little lower than 1.1. This is certainly a small inconsistency in the software.

 

Hi All,
1. For push boats of the Bulgarian fleet on the rivers Danube bow outlines are adopted a type "sledge" without or with a slightest deadrise of the bottom. Three of them made in Holland by the Dutch project, remaining are projected and made in Bulgaria. For these push boats model tests in Vageningen - Holland are made and in the Shipbuilding experimental pool on hydrodynamics in city Varna - Bulgaria / see the files/.
So that I do not have any doubts on outlines adopted in a fore.
2. A general water drag at movement of the barges composition together with a push boat is much higher than resistance of the push boat. So that as far as there was the wave resistance of the push boat, it is minor value in relation to general resistance of a composition from which velocity of the composition and necessary power for pushing depends.
3. Breadth B=9m corresponds to a barges composition in the rivers of Brazil. For the rivers Rhine - Майн- Danube is recommended optimum breadth of section of the composition 11,2m at a draft 2,3m. Therefore the push boat is suitable and for Europe.

1. У толкачей Болгарского флота на реки Дунай носовые обводы приняты тип „сани“ без или малейшей килеватостью днища. Три из них сделанные в Голландии по голландском проекте, остальные проектированы и сделаны в Болгарии. Для этих толкачей сделаны модельные испытания в Вагенинген - Голландия и в Испытательном бассейне по гидродинамики в городе Варна - Болгария / смотри файлы /.
Так что у меня нет никаких сомнений по принятым в носовой части обводам.
2. Общее сопротивление воды при движении состава вместе с толкачом на много выше чем сопротивление самого толкача. Так что насколько бы ни было волновое сопротивление самого толкача, это является незначительная величина по отношению к общему сопротивлению состава от которого зависит скорость состава и необходимая мощность для толкания.
3. Ширина B=9m соответствует составу в реках Бразилии. Для реках Рейн-Майн-Дунай рекомендуется оптимальная ширина секции состава 11,2m при осадке 2,3m. Следовательно толкач годный и для Европу.
_________________________
NA Razmik Baharyan

 

Glad to see that you're getting close to my theories. The image No. 1 comes from your post # 3. As you can see, the water lines at bow have very different shapes from the images 2 and 3, that respect more hydrodynamics.
Another issue: the tugs also have to navigate alone, without pushing barges, and the bow can make them very difficult to navigate upstream in major European rivers.
These are only opinions that I'd like to discuss, calmly, dispassionately, with you and other members of the forum, if it interests someone.

 

Hi Tansl,
To want a controversy on a concrete problem means to be also competent. But nonprofessionally statement looks that the fore of a river push boat is necessary to be a similar to the fore of a river or a sea tug. All over the world river push boat have such form of the fore what was accepted also by me. Elimination is made only with vessels of the river fleet of Russia. They have sharp form of the fore of the construction waterline, combined with towknees for pushing. It is made for the sake of the double function of the vessel - it is possible to tow and possible to push. Such vessel calls "tow-pusher".
Хотеть дискуссию по конкретной проблеме означает быть и компетентным. Но непрофессионально выглядит утверждение что носовая часть речного толкача надо быть похожей носовой части речного или морского буксира. Во всем мире речные толкачи имеют такая форма носовой части, какую принял и я. Исключение делают только суда речного флота России. У них есть острая форма носовой части конструктивной ватерлинии, сочетанная носовыми упорами для толкания. Это сделано ради двойной функции судна - можно буксировать, можно и толкать. Такое судно называется „буксир-толкач“.
__________________________
NA Razmik Baharyan

 

Hi Rabah,
I do not know how are the tugs in the Russian rivers. What we do know is that any tugboat should be able to push and pull, and even pulling sideways. That does not require them to have a square bows but quite the opposite.
I do not doubt that there may be a reason, that I am not capable of imagining, for a tug seems a shoebox and a river tug, like yours, have such a huge draft. So I would like you to tell us why your project has such atypical bow shapes.
There is the possibility, of course, I'm very much mistaken or unaware of things that would clarify the situation. So I need your explanations. Thanks.

 

All you have to do is Google "Push boats" and you'll get pictures of all kinds of push boats operating on US waterways. These include the small fleet boats, which are primarily intended to handle barges within a fleet, to the much larger line boats, which push blocks of 30 barges or more between ports on the Mississippi-Ohio River systems.

No one pays a lot of attention to hydrodynamics, because these boats spend most of their time behind a barge of some kind.

Most of these boats are built in small yards, and whatever engineering they receive is rudimentary at best. Probably 99% of the smallest boats have been designed and built without a naval architect coming within a mile of them, and I have seen very few plans for these boats, even though I've spent more than 30 years working as an NA on the inland trade. Up until recently, these inland tow boats were not inspected by any regulatory authority, and there are thousands currently operating.

When they do travel light boat (= no barges to push), push boats do so at very low speeds, typically less than 10 knots, so any waves which are generated will be small. Since these boats are intended to push something, even the smallest boats have several hundred horsepower installed, so they have no problems moving around. The larger line boats can have 10,000 HP or more installed.

 

Thanks a lot NSA, these are logical explanations of the situation with this type of vessel. I see that it was not difficult to clarify this issue. Even without using beautiful renderings in Rhino you are able to give convincing explanations.
I have to wonder if these explanations serve to clarify some inconsistencies which, in my opinion, are in the design of Rabah. For example, I do not understand that a boat which, as you say, is built without doing some calculations, regardless of hydrodynamics or other technical considerations, have a stern ready to receive a highly sophisticated propulsion system.
Keep in mind that, apparently, Rabah is not designing a small tugboat but a great tug, based on forms of offshore tugs, to operate in European rivers.

 

I must confess, I haven't kept up with Rabah's explanations for his design, except to say he seems to be designing an inland tug, at least, what such a vessel looks like in my experience.

As to the propulsion system, the inland vessels in the US are built with as basic a machinery installation as they can have and still function. The typical arrangement is twin screw with diesel engines driving fixed-pitch props thru reduction gears and regular line shafting. Most of the smaller boats are open wheel (no nozzle), but the higher powered boats typically are fitted with Kort nozzles for additional thrust.

The steering installation is also quite basic: spade type rudders typically fashioned from flat plate. There are two steering rudders fitted aft of the propellers, and some of the larger boats might have one or two pairs of flanking rudders fitted ahead of the propellers for additional turning capability. And by spade type rudders, I mean a single plate which is fitted with a rudder stock, not a built-up rudder which is faired or streamlined like on larger vessels.

The use of azimuthing thrusters as shown on Rabah's design is pretty much unknown on US rivers.

A few of the large line boats experimented with triple screw propulsion, but I think the majority of vessels operating now are twin screw.

There are some harbor tugs and offshore tugs which have been built in recent years with different propulsion arrangements. Some of the newer harbor tugs use Voith-Schneider tractor-type propeller systems for additional maneuverability at the expense of additional draft requirements to clear the bottom of the V-S tractor blades. These vessels do not use conventional rudders, but are highly maneuverable, and some vessels can turn within their own length. These harbor tugs rarely venture into a river system and typically operate only in harbor, assisting larger vessels to and from their berths.

Azimuthing thrusters have been specified on newer supply vessel designs and there may be some offshore tugs built with these systems as well, but the inland river tugs will stay away from these systems because the debris which is frequently carried by the rivers, like submerged logs and such, could wreck these systems if it got sucked into the nozzle or struck the thruster.

 

NavalSArtichoke, I have enough experience in design and construction of harbor and offshore tugs and that's why I say that the forms of Rabah (Figure 1 post # 20) are not suitable for river towboat. Although you can not know the exact figure, the L / B and B / T ratios of hulls in figures 2 and 3 are undoubtedly very different from figure 1.
Very interesting your explanation of tugs for American rivers. Thank you very much.

 

American inland river "tow boats" (which actually push, not tow, barges) have completely different proportions and shapes than harbor and offshore tugs.

https://en.wikipedia.org/wiki/Pusher_(boat)
http://www.towboatphotography.com/
https://www.flickr.com/groups/603110@N20/

 

Since US towboats are not really engineered in a real sense as you understand it (more like a craft tradition where a new boat copies the dimensions and arrangement of a previous boat), L/B or B/T ratios don't mean much.

Push boats do have one advantage over conventional tugs: their stability requirements are much less severe. These boats are not equipped to tow something using a stern winch and hawser, so tripping is not a concern. Most small pushboats are operated with barely any freeboard, usually just enough to keep the main deck from getting wet during normal operation.

It's a different world on the inland waterways of the US. I'm sure the same can be said of the inland waterways of western Europe.

 

Speaking of L/B and B/T I was not thinking exactly on the stability but that, probably, "river tow boats" (I note your correction)need to reduce their draft so for the same displacement, should increase their breadth.
The freeboard, as you say, need not to be high, which also influences the ratios of the dimensions.
The wider the boat, the better it will push barges. And other operating conditions that indeed make the hull of a "river push boat" is quite different from a tugboat.

 

Hello boys,
I guess that which has compared my model with a box for shoe, he not be ashamed at all from his natural ignorance.
But I with him shall not be occupied!
The remaining ship-building experts will see from attached files, that I have correctly picked the form of the push boat. Three of these files are a part of a text file - task, designed in the Brazilian bureau for designing.
For all that I am glad that in the end all of you have reached the straightening output that this model is for a ship without a towing gear.
My model it not a tow! It is a linear river push boat for pushing barges with ethanol in the rivers Tiete-Parana.
You can see better the bottom in the file made on Rhino.
All talks about that a fore is necessary to be pointed or that it is not necessary to mount Azimuting installations because of fear of their damage, is the complete nonsense!

Я предполагаю что тот который сравнил мою модель коробкой для обуви, он вообще не стыдиться от собственной невежественности.
Но я с ним не буду заниматься!
Остальные судостроительные эксперты увидят от прикрепленных файлов, что я правильно выбрал форму толкача. Три из этих файлов являются частью текстового файла - задание, разработанного в Бразильское бюро для проектирования.
Все- таки я рад что в конце концов все вы дошли до правильного вывода что эта модель для судна без буксирного устройства.
Моя модель это не буксир! Это линейный речной толкач для толкания барж с этанолом в реках Тиете-Парана.
Можете посмотреть более хорошо днище в файле сделанный на Rhino.
Все разговоры о том что носовая часть надо быть заостренной или что не надо монтировать Азимутные установки из-за опасения их повреждения, это полные ерунда!
________________________
NA Razmik Baharyan